In prior constructions such as disclosed in U.S. Pat. Nos. 3,432,880 and 3,432,881 eccentric elements for producing taumel action, have employed solid eccentric bolts which pivot within bearings respectively associated with the ring and spur gears. Such bolts are normally constructed with larger and smaller cylindrical surfaces having offset axes to produce eccentric relationship and, as in the prior art patents referred to above, the larger diameter may be fitted with an added external coupling to provide a drive connection between opposed driving and slave hinge units on opposite sides of the seat.